Pressure effect on the energy structure and superexchange interaction of the undoped orthorhombic La2CuO4: beyond the low-energy approximation

摘要

Using LDA+GTB multi-band approach, we studied the compression dependence ofthe electronic structure and in-plane superexchange interaction J(P) in theantiferromagnetic La214 at the 0% and 3% - hydrostatic and unaxial (along caxial) compression. We obtained the superexchange interaction J(P=0)~0.15eV isenhanced by ~20% under the 3% - hydrostatic compression and vice versa the J(P)is decreased slightly by ~5,7% under the 3% - uniaxial compression. In bothcases the J(P) correlates with the in-plane hopping parameters anddd-excitation energy \delta_s=e(^3B_{1})-e(A_{1})$ involving the the two-holestates: Zhang-Rice singlet and ^3{B_{1}} triplet states. The spectral densityof the first removal states is a combined singlet-triplet character and a signof changes in the one with the pressure clearly reproduces the\vec{k}-distribution of quasiparticle states with a different a_1- andb_1-symmetry over the Brillouin zone as a whole.